Tuning mechanism



Oc`t. 14, 1941. a. A. scHwA-Rz ET AL 2,253,815

TUNING MECHANISM Filed July 17, 1940 fir f nventors Patented Oct. Y14, 17941 i.'

TUNING MECHANISM Bertram A. Schwarz and Ludwig Fichter,

Kokomo, Ind., assignors to General Motors Corporation, Detroit, Mich., a corporation of Dela- Application July 17, 1940, Serial No. 346,032

(Ci. i4-10) 13 Claims.

This invention relates to radiov receiving sets and more particularly to means for tuning the same to certain desired stations. Recently a large number of the commercial broadcast receivers lhave had incorporated therein automatic or push button tuning means lwhereby the receiver maybe `tuned by a mere operation oi a push button to bring in a predetermined station to which that particular button has been pre-set. The number of automatic push buttons of course varies with the particular receiver and may be any number, depending upon what the manufacturer might consider as being sufficient to handle all the stations commonly used by the owner. Of course it is necessary to originally adjust each of these buttons to the stations which the listener ordinarily utilizes, but after an original adjustment when pressure is applied to any one button that particular broadcast station will be received on the-set. y

A device for procuring this type of operation is shown in a copending application Serial No. 319,044, filed February 15, 1940, in 4the names of Bertram A. Schwarz and Ludwig Fichter. For purposes of illustration in that application a plurality of push buttons were shown, and also one control which might be called the manual tuning means. 'Ihe purpose of the latteris to bring in any other station whichmaybe desired and is not set up on one of the automatic buttons. In that instance, however, it was necessary to press the manual button inwardly and have it locked in, that position before it could `be rotated to manually tune the receiver. However, most operators are `accustomed to merely rotating a manual control to tune the set to any desired position instead of rst pressing it in. l

It is an object of the present invention therefore to provide a manual tuning means for a receiver having automatic tuning means which may be actuated merely by the rotation of said manual control.

It is a further object of our invention to pro'- vide a manual means for tuning a radio receiver wherein rotary -motion of the knob to be grasped provides longitudinal motion for locking and gear engaging means.

With the above and other objects in view, the

embodiment of our invention'will be best -understood by reference to the following specification and claims and the illustrations in the accompanying drawing, in which:

Figure 1 is the front elevation of theV tuning portion of a receiver;

Figure 2 is an enlarged sectional view takenon .v line 2-2 of Figure 1;

Figure 3 is a detail view ci the axial force producing-means shown in Figure 2, `but showing. the parts in a different position of operation; and, j 1 2 Figure 4 is a sectional view similar to Figure 2 showing all of the control parts in their operating position for tuning.

Referring now more specifically to the drawing, v there is illustratedin Figure 1 a` front panel 2` having therein anA opening I` through which a scale` 6 is visible and over which a small indicating needle may operate. Directly'below the` scale there is provided a series of automatic push buttons Ill which are operated by longitudinal movement. Above each of the buttons is a small U.

indicia plate I2 which may identify the particular station to be obtained by the operation of that,

button. At the lower left-hand portion of the panel is provided a switch and volume control i4, ,Y and tothe lower right-hand portion a manual` tuning control I6.

Directly behind this panel 2 there is provided a box-like casing I8 vwhich houses the mechanism t for both automatically and manually tuning the` receiver, and rotatably supported across this cas- A ing is a shaft 20 which may be connected to the adjustable tuning means of the receiver. Mountedupon this shaft is a substantially large gear 22 which through apparatus .to be described will manually cause a turning ofthe control shaft 2li for tuning purposes.

The automatic buttons I0 are each mounted on the end of a shaft 24 which is supported by two aligned openings in the front and rear walls 26 and 28 respectively of the casing. Between their two'supports they are threaded over a considerable portion of their length. such as shown at 30, and carry thereon a U-shaped traveling nut 32 which engages a transverse rod mounted upon the ends of a pair of levers such as 3S, the opposite ends ofthe latter being connected to the shaft 2li adjacent opposite ends thereof. In this manner the `transverse rod 34 is rigidly connected to and eccentric to the shaft 20 and any rotation of the former about the axis of the latter will cause a turning of the shaft and tuning of thereceiver.

'I'he end -of the rod 24 which projects through the back wall 28 of the casing carries a small tapered head or button 38. There is also carried by the rear wall 28 ,a pivoted plate .lo which is spring-biased to its upper position. 'I'his plate as best shown in Figure 2, has a tapered upper surface which substantially corresponds to the tapered surface of the heads of the buttons these tapered surfaces force the plate ,40 downwardly until they pass beyond the tip which then snaps up behind the head and locks the rodin its innermost positionf Upon the actuation of V38 so that as the rods 24 are forced inwardly I another of the rods the plate will of course be y tends a short distance inside the front Wall 26` of the casing. There is then mounted upon the lower surface of the casing I8 a U-shaped supporting bracket 45 which has an opening 48 in its forward wall in which is carried a cylindrical bushing member 50 having a central opening 52 therein which journals one end of a stub shaft 54. This stub shaft proceeds to a location adjacent the upstanding rear portion of the U-shaped bracket 45 where it has secured thereto a cylindrical worm faced gear member 56 having gear teeth 58 on its rearwardly projecting face. This gear member 56 isformed of a long cylindrical sleeve 51 which immediately surrounds the inner end of the shaft 54 and has cut therein two diametrically opposed slots 59 through which a. pin, later to be described, may project to prevent the same from turning on the shaft, but allowing axial movement. There is also mounted upoln the end of the shaft a small washer 6I which is of slightly larger dimension than the shaft and seats in a circular opening 63 in the end of the gear56 to prevent it from coming off the shaft. These gear teeth 58 are adapted to engage the gear teeth onA the gear Wheel 22. The outer sur face of this member 56 fits into a circular opening 68 in the rear wall of the bracket 45 and this trunnions this end of the shaft 54.

Mounted upon the shaft 54, but freely movable with respect thereto, is a circular disc member 62 which is spring-biased toward the left-hand end of the shaft 54 by a plurality of small tension springs 64, one end of which is connected to the disc 6 2, the opposite end being staked'into the forward bracket wall. Several of these are used which are spaced peripherally'around the disc. Protruding axially from the left-hand face ot the disc 62, as viewed in Figure 2, are a plurality of peripherally spaced triangular tongues 65 indented`sllghtly from the outer periphery thereof. These are adapted to enter triangularly shaped grooves 66 in the bushing member 5l), the arcuate dimension of the tongues 65 being considerably less than the arcuate dimension at the edge of the grooves 66. and also the taper on the tongues 65 is considerably higher than that upon the edge of groove 66 so that there may be relative movement between the two and as a result thereof the points of the triangular tongues may ride up on tapered surfaces of grooves 66; causing relative axial movement between the two. Several of these tongue and groove assemblies are applied at spaced peripheral portions so that any tendency to axially force the two apart upon relative movement will cause this force to be applied at a suiiicient number of spaced peripheral points that there will be no binding on the center shaft.

At approximately the same radius and on the opposite face of the disc 62 is provided a circular ring of axially extending teeth 68. Also mounted upon` the outer surface of the cylindrical sleeve 5`1 encompassing shaft 54 and immediately to the rear of the disc 62 just described is a circular member 10 which is secured to the shaft 54 by 4a pin 12 which extends diametrically through the shaft and a portion of the member 16 so that this member is restrained to move with the shaft 54. This pin also extends through the slots 59 in the sleeve 51 inasmuch as the sleeve acts as a bearing for the member 10. This construction allows the gear 56 to be spring-biased against the mating teeth of the wheel 22.

In the outer surface of the left-hand end of the member 18 there is provided a groove 14 Within which is mounted one end of a plate sector 16,

there being however a substantially loose fit so that the member 10 may rotate within the opening provided in the end of the member 16 but the walls of the groove 14 will cause the plate 16 to move axially upon any movement of the member 10 and the shaft 54. 'I'he inner diameter of the member 10 is substantially the same as the outer diameter. of the sleeve 51, and encircling vthis portion and. concentric with shaft 54 there is provided a small compression spring 11 tending t0 force the two members apart or to maintain the gear 56 against the returning Washer 6l.

The member 16 is a long L-shaped lever which extends through the rear wall 28 of the box-like casing I8 and .has a downwardly projecting lug 18 which is adapted to engage and cooperate with a portion of the spring-biased plate 40 in the same manner as any one of the button heads 38 of the push buttons I0, 'I'his has 4a tapered portion such as ywhich forces the plate downwardly upon inward movement of the lever 16 `and upon its completed inward travel passes beyond a certain notch in the plate to lock in this position in a manner similar to that previously described with respect to the push button rods. Inasmuch as this lever 16 is rigidly secured to the shaft 54 it also locks this shaft in its innermost axial position when the end 18 is locked over the spring biasing lever 40. This causes the teeth 58 to engage with the teeth of the wheel 22 and thereafter any rotation of the shaft 54 will cause the gear 22 to rotate and the set to be tuned. As before mentioned, when the two sets of teeth are in engagement the gear 56 is depressed slightly against the force of the spring 11 which maintains the teeth in contact. This is necesary since the .lug 18 must pass over and beyond its locking position and then return slightly in order to assume the proper position. If the spring 11 were not provided the teeth would contact and the lug would never to able to proceed far enough to lock over the portion of the spring-biased plate 40.

Secured to the rear end of the'small shaft 46 and to the forward end of theshaft 54, which are in alignment, are two spring levers 82 and 84, the free end of each 'being held together by suitable rivets or bolts such as 86. This member provides a drive from one shaft to another and at the same time allows the two to be moved relatively axially. 'Ihe large plate lever 16 is also spring-biased toward the fiont of the assembly by tension spring 88, one end being connected to the plate K16 and the other to the bracket 46. The operation of this particular drive will now be described.

As the operator of the set grasps the manual y knob I6 andturnsthe same, shaft 46 will rotate in bushing 44. This motion will be transmitted through the spring coupling 82, 86, 84 to the small stub shaft 54. The member l0, which is the only member rigidly secured to the shaft l, will then rotate and the small triangular projections 89 which extend axially from the forward face of this member l0 begin to ride up on the mating triangular teeth 68 on the rear face of the disc 62. The friction between these two substantially parallel surfaces, however, is quite high and more than the friction between the triangular member 65 and the triangular grooves 66 in the member 50. The first action, therefor, will be that the disc 62 will rotate with the member l0 and the triangular portion 65 riding up on the triangular surfaces 66 will cause both the disc 62 and the disc 10, which we must remember carries the shaft 54, to move to the right or rearwardly. When the triangular portion 65 has ridden up on surfaces 66 to a position adjacent the edge of the member, the square tip 9D will stop against the axial wall 92 and prevent the disc 62 from rotating any further or riding up.

At this point the friction between the projections 89 and teeth 68 is less than that between tip 90 and member 92 and gives away to cause a sliding or relative axial motion between the members 62 and 10. Thus B2 ceases any further axial movement, but l0 and shaft 54 continue to move a short additional amount, This additional amount should be suflicient to lock the u lug 18 over the locking plate 40 and at the same time cause gear teeth 58 to engage the Wheel 22. Any further rotation will of course cause the teeth 89 to pass beyond the tip of the engaging teeth 68 and the disc 62 will then snap back into the triangular recess 66 and be entirely out of the way. Any further rotation of the manual knob I6 will then merely cause the drive between the gear teeth 58 and 22 to tune the set. These various steps are best illustrated in the drawings where Figure 2 shows the same in their inactive or rest position, Figure 3 shows the drive members in the position just prior to latching or when both sets of teeth have ridden up on the sloping triangular portion so provided, and Figure 4 shows the locked-in position where any further turning will merely tune the set. It-

will also be obvious from the drawing that the manual knob I6 may be turned in either direction to lock in since the surfaces 66 and teeth 68 are tapered in both directions. With the locking in members now disengaged, it will be evident thatwe have provided a simplemechanism by which the operator can manually tune a receiver and automatically tune by merely rotating a control knob, which he has been in the custom of doing, it not being necessary for him to depress or lock in the manual drive before he actually manually tunes the set over the band.

We claim:

l. In a control device, a frame; a shaft rotatably mounted in the frame, a gear mounted thereon, a second shaft mounted in the frame for both rotative and axial movement, driving means on the second shaft adapted to engage the gear in a given position, means. for locking said second shaft in one extreme axial position, means to move said second shaft axially upon rotation thereof and means to rotate the second shaft whereby such rotation will cause axial movement to locked position when the driving means will be in engagement with the gear to drive the first shaft.

2. In a control device, a frame, two rotatable shafts mounted in said frame, driving means carried by both shafts for interengagement, one of said shafts being capable of axial movement whereby the driving means may be disengaged, camming means mounted on said axially movable shaft and on the frame adjacent thereto to cause axial movement thereof upon rotation of said shaft and means for rotating said last named shaft whereby said rotation will cause the axially movable shaft to move to a position in which the driving means between the two shafts is in interengagement and the other shaft will be rotated.

3. In a control device, a frame, two rotatable shafts mounted in said frame, driving means carried by both shafts for interengagement, one of said shafts being capable of axial movement whereby the driving means may be disengaged, camming means mounted on said axially movable shaft and on the frame adjacent thereto to cause axial movement thereof upon rotation of said shaft, means for rotating said last named shaft whereby said rotation will cause the axially movable shaft to move to a position in which the driving means between the two shafts is in interengagement and the other shaft will be rotated and means for locking the axially movable shaft in this engaging position to maintain drive between the two shafts.

4. In a control device, a frame, a shaft axially and rotatably movable in said frame, camming means carried by the shaft and by the frame adjacent thereto to cause axial movement of the shaft upon rotation thereof, locking means for retaining the shaft in one extreme axial position and resilient means to retract a portion of the cam means to inoperative position when the locking means is effective whereby any further rotation of the shaft will be free from any axial force.

5. In a control device, a frame, a shaft axially and rotatably movable in said frame', camming means carried by the shaft and by the frame adjacent thereto to cause axial movement of the shaft upon rotation thereof,- locking means for retaining the shaft in one extreme axial position,

. resilient means to retract a portion of the cam means to inoperative position when the locking means is effective whereby any further rotation of the shaft will be free from any axial force and a second shaft rotatably mounted in the frame.

interengaging driving means on the two shafts operative when the first named shaft is in its extreme axial locked position whereby no driving action is applied to the second shaft. unless the axially movable shaft is locked against any axial movement.

6. In a control device, a frame, a shaft mounted thereon for both rotative and axial movement, a second shaft mounted in the frame in axial alignment with the rst for rotative movement only, resilient means connecting the two shafts, camming means mounted on the frame and on the first shaft whereby rotational movement thereof will cause axial movement, whereby as the second shaft tends to rotate the first, the first may move axially with respect thereto.

7. In a control device, a frame, a shaft mounted therein for both rotational and axial movement, a bushing mounted on the frame trunnioning one end of the shaft and having cam surfaces thereon, a floating cam ring surrounding the shaft and having portions engaging the cam surfaces of the bushing, resilient means for biasing the ring toward the bushing to maintain the two parts in contact and a third cam member rigidly secured to the shaft cooperating with the floating ring to cause axial shaft movement.

8. In a control device, a frame, a shaft mounted therein` for both Irotational and axial movement, a bushing mounted on the frame trunnioning one end of the shaft and having cam surfaces thereon, a floating cam ring surrounding the shaft and having portions engaging the cam surfaces of the bushing,.resi1lent means for biasing the ring toward the bushing to maintain the two lparts in contact, a third cam member rigidly secured to the shaft cooperating with the floating ring to cause axial shaft movement and resilient means to bias the third cam and shaft toward the. floating ring and bushing to maintain them allincontact.

9. In a control device, a frame, a shaftmounted therein for both rotational and axial movement, a bushing mounted on .the frame trunnioning 'one end of the shaft and having cam surfaces thereon, a floating cam ring surrounding the shaft and having portions engaging the cam surfaces of the bushing, resilient means for biasing the ring toward the bushing to maintain the twd parts in contact, a third cam member rigidly `secured to the shaft cooperating with the floating ring to cause axial shaft movement, resilient' means to bias the third cam'` andV shaft toward the floating ring and bushing to maintain them all in contact and locking means to retain the third cam and shaft in one extreme axial position against thebias of the last named resilient means, said first named resilient means retracting said floating ring from engagement with the third cam when it is so locked.

10. In a control device, a frame, a shaft mounted therein for both rotational and axial movement, a bushing mounted on the frame trunnloning one end of the shaft and having cam surfaces thereon, a iioating cam ring surrounding the shaft and having portions engaging the cam surfaces of the bushing, resilient means for biasing the ring toward the bushing to maintain the two parts in contact, a third cam member rigidly secured to the shaft cooperating with the floating ring to cau'se axial movement and driving means resiliently carried on the opposite shaft end.

11. In a control device, a frame, a shaft mounted therein for 4both rotational and axial movement, a bushing mounted on the frame trunnioning one end of the shaft and having cam surfaces thereon, a floating cam ring surrounding the shaft and having portions engaging the cam surfaces of the bushing, resilient means for biasing the ring toward the bushing to maintain the two parts in contact, a third cam member rigidly secured to the shaft cooperating with the floating ring to cause axial shaft movement, driving 'means resiliently carried on the opposite shaft end, locking means to retain the thirdcam and shaft in one extreme axial position against the bias of the last named resilient means, said first named resilient means retracting said floating ring from engagement with the third cam when it is so locked, a second shaft rotatably carried by the frame, a gear mounted thereon in juxtaposition to the driving means on the first shaft but spaced therefrom in inoperative relation until the first shaft is locked by the locking means and when so locked the two will engage to cause driving of the second shaft.

12. In a control device, a frame, a shaft rotatably mounted in the frame, driving means on the shaft, a second sectional shaft mounted in the frame, driving means adapted to engage the driving means on `the first shaft mounted on one Vend of one section of the second shaft, said last named section being axially movable to cause engagement and disengagement of the driving means, resilient means connecting the two sections of the second shaft so that relative axial movement may occur and cam means to cause said axial ymovement of the axially movable section of the second shaft upon rotation of the rst section whereby the driving means will be engaged and the first shaft driven from the second.

13. In a control device, a frame, a shaft rotatably mounted in the frame, driving means on the shaft, a second sectional shaft mounted in the frame, driving means adapted to engage the driving means on the first shaft mounted on one end of one section of the second shaft, said last named section being axially movable to cause engagement and disengagement of the driving means, resilient means connecting the two sections of the second shaft so that relative axial movement may occur and cam means to cause said axial movement of the axially movable section of the second shaft upon rotation of the first section whereby the driving means will be engaged and the first shaft driven from the second and locking means to maintain the driving connection when the second shaft section has moved into driving relation.

BERTRAM SCHWARZ. LUDWIG FIGHTER.

CERTIFICATE OF' CORRECTION. l Patent No. 2,258,815. october 1h, 191,11.

BERTRAM A. SCHWARZ, ET AL.

It is hereby certified that error appears in the printed specification ofthe above numbered .patent requiring correction as follows: Page L1, first column, line 14,6, claim lO, after the word "axiel" inserti sha-ft--g and that the said Letters- Patent should be readwith this correction therein that the same may 'conform' to the record of the oase in the Patent Offioe.

signed and sealed this l.2nd dey ef December, A. D. 19m.-

Henry Van Arsdaie, (Seal) A Acting Commissioner of Patents. 

